In my experience with studying, keeping and breeding discus fish the most common cause of health problems is incorrect water conditions. Discus care has very little to do with fish. It is about water chemistry, and if you are not knowledgeable enough to maintain the proper water conditions, your fish are doomed. In this article I will only discuss a few topics that comprise water chemistry, but I strongly suggest you learn as much as possible. Your fish will live a lot longer and your hobby will be more rewarding if you take the time to do the research.

If I had to pick the most neglected task common to all fish keepers it would have to be testing their water prior to every water change. When it comes to discus care, this is particularly important, as discus are prone to stress easily. Tap water is full of chemicals which are added for YOUR health, but they can be very damaging for your fish. In addition, much of our tap water ultimately comes from rain water. The chemistry of rain water is always changing due to pollution, so it is critical that you monitor levels at every water change.

Chloramine and Chlorine
Chlorine or chloramine are routinely added to the water supply in many parts of the world. Chlorine is not good for discus fish and chloramine is worse. The presence and concentration of either can be determined with a test kit. Removal of chlorine or chloramine is part of the process known as conditioning your water and is an essential part of discus care.

Water Hardness and Alkalinity
If the hardness and alkalinity are not correct for your discus, they may be adjusted. It is easier to increase hardness and alkalinity upwards rater than downwards, but lowering these values is by no means impossible, it just requires an extra water conditioning step.

About pH
Discus are somewhat picky about pH. Keep your pH below 7 and above 5.5. The ideal pH for discus is 6. At pH levels above 7, discus are stressed. Below 5.5, the pH is inclined to drop rapidly, so I find 6 to be comfortable for both the fish and the fish keeper.

This has been a brief overview of water chemistry as it relates to discus care. This only covers the high level basics, and there are times such as breeding when special care must be taken to ensure proper conditions. In general, discus are not difficult to care for, as long as you give them what they want. And, what they want is clean water, free of toxins, and the correct chemistry.